In a gas mask, a nosecup is used to prevent humid air that is exhaled from contacting the eye pieces of the mask and causing fogging problems. A one-way valve is required in the nosecup to allow fresh air in. Current gas masks use a rigid metal valve body crimped onto a hole in the nosecup or a rigid plastic valve body glued into place in a hole in the nosecup. Even if the valve seat is molded with the nosecup, the seat is still made in a rigid form. The valving element used is also a flat, resilient disk which seals by covering the valve seat.
An example of the known prior art is shown in U.S. Pat. No. 2,051,023 which issued on Aug. 18, 1936, to E. W. Bullard. Bullard's valve consists of a valve seat which is molded with the facepiece. However the seat is held in a rigid shape by the use of a metal ring which is embedded within the seat. The valving element is a flat resilient disk which is lightly held on the valve seat mainly by inhalation by the wearer. The present invention aims at the provision of a valve that is simpler and less expensive to produce.